Polyp - A benign growth that protrudes from a mucous membrane.
Positron emission tomography (PET) - A procedure in which a small amount of
radioactive dye (sugar) is injected into a vein, and a scanner is used to make detailed,
computerized pictures of areas inside the body where the dye travels; also called PET
scan. Because cancer cells often use more glucose than normal cells, when combined
with a radioactive glucose (sugar) called FDG, the pictures can be used to find cancer
cells in the body, including micrometastases; this type of procedure is called FDG-PET.
Prevalence - the number or percent of people alive on a certain date in a population
who previously had a diagnosis of the disease. It includes new (incidence) and pre-existing cases, and is a function of both past incidence and survival.
PD1 (Programmed death- 1) - A protein on the surface of immune cells called T cells
(see T cell). When PD1 attaches to PDL1 on other immune cells, it sends signals into
the T cells to tell them to slow down and stop acting aggressively. Thus, PD1 acts as
an immune checkpoint protein.
Prostate Cancer – A form of cancer that starts in tissues of the prostate (a gland in
the male reproductive system found below the bladder and in front of the rectum). In
men, it is the most frequently diagnosed cancer and the second most common cause
of death from cancer.
Prostatic Specific Antigen (PSA) - A protein secreted by the prostate gland,
increased levels of which are found in the blood of patients with cancer of the
prostate.
Protein - A molecule made up of amino acids that is needed for the body to function
properly.
Radiation - Energy released in the form of particle or electromagnetic waves.
Common sources of radiation include radon gas, cosmic rays from outer space,
medical x-rays and energy given off by a radioisotope (unstable form of a chemical
element that releases radiation as it breaks down and becomes more stable).
Radiotherapy - The use of high-energy radiation from x-rays, gamma rays, neutrons,
protons and other sources to kill cancer cells and shrink tumors. Radiation may come
from a machine outside the body (external-beam radiation therapy), or it may come
from radioactive material placed in the body near cancer cells (internal radiation
therapy). Systemic radiotherapy uses a radioactive substance, such as a radiolabeled
monoclonal antibody, that travels in the blood to tissues throughout the body. Also
called irradiation and radiation therapy.
Receptor – A protein in a cell that attaches to specific molecules, like hormones, from
outside the cell, in a lock-and-key manner, producing a specific effect on the cell, for
example, initiating cell proliferation. Receptors are most commonly found spanning the
membrane surrounding a cell but can be located within cells.
Renal cell carcinoma - The most common type of kidney cancer. It begins in the
lining of the renal tubules in the kidney. The renal tubules filter the blood and produce
urine. Also called hypernephroma, renal cell adenocarcinoma, and renal cell cancer.
Signaling pathway/signaling network - A group of molecules in a cell that work
together to control one or more cell functions, such as cell proliferation or cell death.
After the first molecule in a pathway receives a signal, it activates another molecule.
This process is repeated until the last molecule is activated and the cell function
involved is carried out. Abnormal activation of signaling pathways can lead to cancer,
and drugs are being developed to block these pathways. This may help block cancer
cell growth and kill cancer cells.

Standard of care – The intervention or interventions generally provided for a certain
type of patient, illness or clinical circumstance. The intervention is typically supported
by evidence and/or expert consensus as providing the best outcomes for the given
circumstance.
Surrogate endpoint - A biomarker intended to substitute for a clinical endpoint (see
Endpoint). Surrogate markers are used when the primary endpoint is undesired (e.g.,
death), or when the number of events is very small, thus making it impractical to
conduct a clinical trial to gather a statistically significant number of endpoints. The FDA
and other regulatory agencies will often accept evidence from clinical trials that show
a direct clinical benefit to surrogate markers.
T cell - A type of immune cell that protects the body from invading microorganisms
and other foreign substances, and destroys infected and malignant cells. A T cell is a
type of white blood cell; also called T lymphocyte.
The Cancer Genome Atlas (TCGA) - A project to catalogue genetic mutations
responsible for cancer, started in 2005. The goal of the project is to provide systematic,
comprehensive genomic characterization and sequence analysis of different types of
human cancers.
Treatment vaccine - A type of therapy that uses a substance or group of substances
to stimulate the immune system to destroy a tumor or infectious microorganisms such
as bacteria or viruses.
Triple-negative breast cancer – A form of breast cancer that lacks expression of
three proteins that can be targeted to treat breast cancer: HER2 and the specific
proteins, called receptors, that the hormones estrogen and progesterone attach to, the
estrogen receptor and the progesterone receptor.
Tumor - An abnormal mass of tissue that results when cells divide more than they
should or do not die when they should. Tumors may be benign (not cancer), or
malignant (cancer); also called neoplasm.
Tumor microenvironment - The normal cells, molecules and blood vessels that
surround and feed a cancer cell. A cancer can change its microenvironment, and the
microenvironment can affect how a tumor grows and spreads.
Tumor suppressor gene - A type of gene that makes a protein called a tumor
suppressor protein that helps control cell growth. Mutations (changes in DNA) in tumor
suppressor genes may lead to cancer; also called an antioncogene.
Vaccine - A substance or group of substances meant to cause the immune system to
respond to a tumor or to microorganisms, such as bacteria or viruses. A vaccine can
help the body recognize and destroy cancer cells or microorganisms.
VEGF (Vascular endothelial growth factor) – A family of signaling proteins that bind
to molecules called VEGF receptors, found mostly on the surface of cells lining blood
and lymphatic vessel walls, causing an increase in the number or branches of blood
and lymphatic vessels.